Ok, here we go. The red marked fuzes were to be used with guns with higher gas pressures than the 37mm. Means the red ones were used from 50mm and higher.
Difference:
The wall thickness between the tracer cavity and the cavity holding the mechanical parts was increased to withstand higher gas pressures.
Red marked fuzes are 1mm longer than the white ones. Means the said wall thickness is supposedly 1mm thicker.

5103*

Originally Posted by x

Ok, here we go. The red marked fuzes were to be used with guns with higher gas pressures than the 37mm. Means the red ones were used from 50mm and higher.
Difference:
The wall thickness between the tracer cavity and the cavity holding the mechanical parts was increased to withstand higher gas pressures.
Red marked fuzes are 1mm longer than the white ones. Means the said wall thickness is supposedly 1mm thicker.

Hi x
It does not seem like it
Wall thickness not solve blowing through the thread that is the path of least resistance